Heart valves are commonly provided with a suturing or sewing ring which may be of fabric, the suturing ring being sewed by the surgeon to the peripheral tissue of a natural heart valve orifice after surgical removal of damaged or diseased natural valve structure. Following implantation, the surgeon may desire to adjust the valve by rotation of the valve body within the suturing ring so that the valving mechanism can properly operate without interference from surrounding heart tissue. Adjustment by rotation of the valve body should require a rotational force sufficiently small as to avoid damage to the sutured heart tissue or loosening of the sutures, and yet sufficiently great so that the valve, when properly positioned, does not further rotate when it is placed in operation. On the other hand, the suturing ring should be held tightly to the valve body so as to prevent the valve body and suturing ring from separating at their edges. Further, the method of manufacture of the valve should be such as to render the valve reliably rotatable within the ring within a narrow range of torque values; that is, the amount of torque needed to rotate the valve within the suturing ring should be substantially the same from one valve to another of the same size.
A number of methods have been proposed for retaining suturing members on heart valves, and certain of these methods have been summarized in U.S. Pat. No. 3,800,403. The last-mentioned patent describes a suturing ring which is provided with a heat-shrinkable annular plastic band. The valve body and surrounding suturing ring are heated to cause the band to shrink and to clamp the suturing ring onto the valve. The suturing ring itself is a torus-like element made of fabric, and the heat-shrinkable plastic band is positioned in the interior of the ring. Thus, during the shrinking operation, the band is hidden from view so that actual visual observation of the precise manner in which the heat-shrinkable band is clamped or positioned about the valve body is not possible. U.S. Pat. No. 3,623,212 disclosed a suturing ring which is held by means of threads or cords onto a valve body. Different ones of the threads, of course, exert different clamping pressures, and hence the clamping force across the width of the suturing ring may be uneven and the torque required to rotate the valve body within the ring is unpredictable.
It would be desirable to provide a heart valve body with a suturing ring in which attachment of the suturing ring to the valve body could be closely visually observed so as to detect and avoid any defects in material or errors in alignment of the components of the suturing ring on the valve body. It would further be desirable to provide such a valve which would permit the valve body to be rotated within the suturing ring upon application to the body torque within a narrow, predetermined range. It would further be desirable to so attach a suturing ring to a valve body as to substantially prevent the ring from being normally pulled even slightly away from the body.